docs: def refresh(self) -> None:
          """
          Reloads all sources that are registered with this server.
          """
          logger.info('refreshing sources')
          for source in list(self):
              self.unload(source)
  
          if not os.path.exists(self.__registry_fn):
              return
  
          # TODO add version
          with open(self.__registry_fn, 'r') as f:
              registry = yaml.load(f)
          assert isinstance(registry, list)
  
          for source_description in registry:
              source = Source.from_dict(source_description)
              self.load(source)
  
          logger.info('refreshed sources')